Barbells used in weight lifting exercise include an elongated lifting bar having interchangeable weights slidably mounted on each end thereof and held thereon by a locking collar. The conventional locking collar comprises a sleeve slidably mounted on each end of the bar and held against the face of the weights by a set screw tightened down against the lifting bar. These locking collars have not been entirely satisfactory because they have a tendency to become loose during the exercise workout, resulting in the weights sliding off the end of the lifting bar, thereby causing injury to the weight lifter and others who might be in the vicinity.
To overcome the disadvantages experienced with the conventional locking collars, a clamping collar of the type disclosed in U.S. Pat. No. 4,579,337, dated Apr. 1, 1986, has been proposed wherein a ball detent is operably connected between the lifting bar and a pair of threadably interconnected cylindrical members. While this type of clamping collar is satisfactory for its intended purpose, its disadvantage is characterized by its plurality of moving parts, and the manipulation required to turn one cylindrical member relative to the other to move the ball detent into the locked or unlocked positions.
To overcome the disadvantages experienced with the prior art barbell clamping collars, after considerable research and experimentation, the clamp of the present invention has been devised which comprises, essentially, a hub member slidably mounted on an end portion of a lifting bar. A pair of semi-circular cooperating jaws are pivotally connected to the hub member, and are spring-biased to a closed, clamping position for engaging a grooved portion in the lifting bar. The clamp is manually actuated to the open position by squeezing handle members provided on the semi-circular jaws to pivot the jaws in a direction away from each other against the biasing force of the spring. By the construction and arrangement of the clamp of the present invention, a clamp is provided which will not become loose during the exercise workout, and is easily manipulated to the open and closed positions. The clamp has fewer moving parts, whereby it is not likely to become inoperable even after long and continued use.